A Micro Electro-Mechanical Systems (MEMS) device comprises a relatively small electro-mechanical device fabricated on a substrate (e.g., a silicon substrate) using process techniques similar to those employed to manufacture integrated circuits. Examples of MEMS devices include sensors (e.g., acceleration sensors) and switches (e.g., RF switches for cell phone applications). Due to their small size, these MEMS devices may be sensitive to contamination from the surrounding environment, as the infiltration of small particulate matter into a MEMS device can severely impact the device's operation. Thus, a MEMS device is typically sealed within a hermetic cavity.
A hermetic cavity for a MEMS device may be created by forming a seal ring around a periphery of the MEMS device and attaching a lid to the seal ring. The seal ring and lid define a cavity surrounding the MEMS device, with the seal ring providing a hermetic seal between the lid and the underlying substrate. However, poor adhesion of the seal ring material (e.g., gold) to the underlying substrate (e.g., silicon) may lead to delamination of the seal ring and/or a low resistance to shear loads. Should the seal ring fail (e.g., due to delamination and/or shearing), the operation of the enclosed MEMS device can be dramatically affected, as noted above.